Hybrid maize plant &amp; seed (3231)

ABSTRACT

According to the invention, there is provided a hybrid maize plant, designated as 3231, produced by crossing two Pioneer Hi-Bred International, Inc. proprietary inbred maize lines. This invention relates to the hybrid seed 3231, the hybrid plant produced from the seed, and variants, mutants, and trivial modifications of hybrid 3231.

FIELD OF THE INVENTION

This invention is in the field of maize breeding, specifically relating to a hybrid maize line designated 3231.

BACKGROUND OF THE INVENTION Plant Breeding

Field crops are bred through techniques that take advantage of the plant's method of pollination. A plant is self-pollinated if pollen from one flower is transferred to the same or another flower of the same plant. A plant is cross-pollinated if the pollen comes from a flower on a different plant.

Plants that have been self-pollinated and selected for type for many generations become homozygous at almost all gene loci and produce a uniform population of true breeding progeny. A cross between two different homozygous lines produces a uniform population of hybrid plants that may be heterozygous for many gene loci. A cross of two plants each heterozygous at a number of gene loci will produce a population of hybrid plants that differ genetically and will not be uniform.

Maize (Zea mays L.), often referred to as corn in the United States, can be bred by both self-pollination and cross-pollination techniques. Maize has separate male and female flowers on the same plant, located on the tassel and the ear, respectively. Natural pollination occurs in maize when wind blows pollen from the tassels to the silks that protrude from the tops of the ears.

The development of a hybrid maize variety involves three steps: (1) the selection of plants from various germplasm pools for initial breeding crosses; (2) the selfing of the selected plants from the breeding crosses for several generations to produce a series of inbred lines, which, although different from each other, breed true and are highly uniform; and (3) crossing the selected inbred lines with unrelated inbred lines to produce the hybrid progeny (F₁). During the inbreeding process in maize, the vigor of the lines decreases. Vigor is restored when two different inbred lines are crossed to produce the hybrid progeny (F₁). An important consequence of the homozygosity and homogeneity of the inbred lines is that the hybrid created by crossing a defined pair of inbreds will always be the same. Once the inbreds that create a superior hybrid have been identified, a continual supply of the hybrid seed can be produced using these inbred parents and the hybrid corn plants can then be generated from this hybrid seed supply.

Large scale commercial maize hybrid production, as it is practiced today, requires the use of some form of male sterility system which controls or inactivates male fertility. A reliable method of controlling male fertility in plants also offers the opportunity for improved plant breeding. This is especially true for development of maize hybrids, which relies upon some sort of male sterility system. There are several options for controlling male fertility available to breeders, such as: manual or mechanical emasculation (or detasseling), cytoplasmic male sterility, genetic male sterility, gametocides and the like.

Hybrid maize seed is typically produced by a male sterility system incorporating manual or mechanical detasseling. Alternate strips of two inbred varieties of maize are planted in a field, and the pollen-bearing tassels are removed from one of the inbreds (female). Providing that there is sufficient isolation from sources of foreign maize pollen, the ears of the detasseled inbred will be fertilized only from the other inbred (male), and the resulting seed is therefore hybrid and will form hybrid plants.

The laborious, and occasionally unreliable, detasseling process can be avoided by using cytoplasmic male-sterile (CMS) inbreds. Plants of a CMS inbred are male sterile as a result of factors resulting from the cytoplasmic, as opposed to the nuclear, genome. Thus, this characteristic is inherited exclusively through the female parent in maize plants, since only the female provides cytoplasm to the fertilized seed. CMS plants are fertilized with pollen from another inbred that is not male-sterile. Pollen from the second inbred may or may not contribute genes that make the hybrid plants male-fertile. Usually seed from detasseled fertile maize and CMS produced seed of the same hybrid are blended to insure that adequate pollen loads are available for fertilization when the hybrid plants are grown.

There are several methods of conferring genetic male sterility available, such as multiple mutant genes at separate locations within the genome that confer male sterility, as disclosed in U.S. Pat. Nos. 4,654,465 and 4,727,219 to Brar et al. and chromosomal translocations as described by Patterson in U.S. Pat. Nos. 3,861,709 and 3,710,511. These and all patents referred to are incorporated by reference. In addition to these methods, Albertsen et al., of Pioneer Hi-Bred, U.S. patent application Ser. No. 07/848,433, have developed a system of nuclear male sterility which includes: identifying a gene which is critical to male fertility; silencing this native gene which is critical to male fertility; removing the native promoter from the essential male fertility gene and replacing it with an inducible promoter; inserting this genetically engineered gene back into the plant; and thus creating a plant that is male sterile because the inducible promoter is not "on" resulting in the male fertility gene not being transcribed. Fertility is restored by inducing, or turning "on", the promoter, which in turn allows the gene that confers male fertility to be transcribed.

There are many other methods of conferring genetic male sterility in the art, each with its own benefits and drawbacks. These methods use a variety of approaches such as delivering into the plant a gene encoding a cytotoxic substance associated with a male tissue specific promoter or an antisense system in which a gene critical to fertility is identified and an antisense to that gene is inserted in the plant (see: Fabinjanski, et al. EPO 89/3010153.8 publication no. 329,308 and PCT application PCT/CA90/00037 published as WO 90/08828).

Another system useful in controlling male sterility makes use of gametocides. Gametocides are not a genetic system, but rather a topical application of chemicals. These chemicals affect cells that are critical to male fertility. The application of these chemicals affects fertility in the plants only for the growing season in which the gametocide is applied (see Carlson, Glenn R., U.S. Pat. No. 4,936,904). Application of the gametocide, timing of the application and genotype specificity often limit the usefulness of the approach.

The use of male sterile inbreds is but one factor in the production of maize hybrids. The development of maize hybrids requires, in general, the development of homozygous inbred lines, the crossing of these lines, and the evaluation of the crosses. Breeding programs combine the genetic backgrounds from two or more inbred lines or various other broad-based sources into breeding pools from which new inbred lines are developed by selfing and selection of desired phenotypes. The new inbreds are crossed with other inbred lines and the hybrids from these crosses are evaluated to determine which of those have commercial potential.

There are many important factors to be considered in the art of plant breeding, such as the ability to recognize important morphological and physiological characteristics, the ability to design evaluation techniques for genotypic and phenotypic traits of interest, and the ability to search out and exploit the genes for the desired traits in new or improved combinations.

The objective of commercial maize hybrid line development programs is to develop new inbred lines to produce hybrids that combine to produce high grain yields and superior agronomic performance. The primary trait breeders seek is yield. However, many other major agronomic traits are of importance in hybrid combination and have an impact on yield or otherwise provide superior performance in hybrid combinations. Such traits include percent grain moisture at harvest, relative maturity, resistance to stalk breakage, resistance to root lodging, grain quality, and disease and insect resistance. In addition, the lines per se must have acceptable performance for parental traits such as seed yields, kernel sizes, pollen production, all of which affect ability to provide parental lines in sufficient quantity and quality for hybridization. These traits have been shown to be under genetic control and many if not all of the traits are affected by multiple genes.

Pedigree Breeding

The pedigree method of breeding is the mostly widely used methodology for new hybrid line development.

In general terms this procedure consists of crossing two inbred lines to produce the non-segregating F₁ generation, and self pollination of the F₁ generation to produce the F₂ generation that segregates for all factors for which the inbred parents differ. An example of this process is set forth below. Variations of this generalized pedigree method are used, but all these variations produce a segregating generation which contains a range of variation for the traits of interest.

EXAMPLE 1 Hypothetical Example of Pedigree Breeding Program

Consider a cross between two inbred lines that differ for alleles at six loci.

The parental genotypes are:

Parent1 AbCdeF/AbCdeF

Parent2 aBcDEf/aBcDEf

the F₁ from a cross between these two parents is:

F₁ AbCdeF/aBcDEf

Selfing F₁ will produce an F₂ generation including the following genotypes:

    ______________________________________                                                    ABcDEf/abCdeF                                                                  ABcDef/abCdEF                                                                  ABcDef/abCdeF                                                       ______________________________________                                    

The number of genotypes in the F₂ is 3⁶ for six segregating loci (729) and will produce (2⁶)-2 possible new inbreds, (62 for six segregating loci).

Each inbred parent which is used in breeding crosses represents a unique combination of genes, and the combined effects of the genes define the performance of the inbred and its performance in hybrid combination. There is published evidence (Smith, O. S., J. S. C. Smith, S. L. Bowen, R. A. Tenborg and S. J. Wall, TAG 80:833-840 (1990)) that each of the lines are different and can be uniquely identified on the basis of genetically-controlled molecular markers.

It has been shown (Hallauer, Amel R. and Miranda, J. B. Fo. Quantitative Genetics in Maize Breeding, Iowa State University Press, Ames Iowa, 1981) that most traits of economic value in maize are under the genetic control of multiple genetic loci, and that there are a large number of unique combinations of these genes present in elite maize germplasm. If not, genetic progress using elite inbred lines would no longer be possible. Studies by Duvick and Russell (Duvick, D. N., Maydica 37:69-79, (1992); Russell, W. A., Maydica XXIX:375-390 (1983)) have shown that over the last 50 years the rate of genetic progress in commercial hybrids has been between one and two percent per year.

The number of genes affecting the trait of primary economic importance in maize, grain yield, has been estimated to be in the range of 10-1000. Inbred lines which are used as parents for breeding crosses differ in the number and combination of these genes. These factors make the plant breeder's task more difficult. Compounding this is evidence that no one line contains the favorable allele at all loci, and that different alleles have different economic values depending on the genetic background and field environment in which the hybrid is grown. Fifty years of breeding experience suggests that there are many genes affecting grain yield and each of these has a relatively small effect on this trait. The effects are small compared to breeders' ability to measure grain yield differences in evaluation trials. Therefore, the parents of the breeding cross must differ at several of these loci so that the genetic differences in the progeny will be large enough that breeders can develop a line that increases the economic worth of its hybrids over that of hybrids made with either parent.

If the number of loci segregating in a cross between two inbred lines is n, the number of unique genotypes in the F₂ generation is 3^(n) and the number of unique inbred lines from this cross is {(2^(n))-2}. Only a very limited number of these combinations are useful. Only about 1 in 10,000 of the progeny from F₂ 's are commercially useful.

By way of example, if it is assumed that the number of segregating loci in F₂ is somewhere between 20 and 50, and that each parent is fixed for half the favorable alleles, it is then possible to calculate the approximate probabilities of finding an inbred that has the favorable allele at {(n/2)+m} loci, where n/2 is the number of favorable alleles in each of the parents and m is the number of additional favorable alleles in the new inbred. See Example 2 below. The number m is assumed to be greater than three because each allele has so small an effect that evaluation techniques are not sensitive enough to detect differences due to three or less favorable alleles. The probabilities in Example 2 are on the order of 10⁻⁵ or smaller and they are the probabilities that at least one genotype with (n/2)=m favorable alleles will exist.

To put this in perspective, the number of plants grown on 60 million acres (approximate United States corn acreage) at 25,000 plants/acre is 1.5×10¹².

EXAMPLE 2 Probability of Finding an Inbred with M of N Favorable Alleles

Assume each parent has n/2 of the favorable alleles and only 1/2 of the combinations of loci are economically useful.

    ______________________________________                                         No of   No. of favorable                                                                           No. additional                                             segregating                                                                            alleles in Parents                                                                         favorable alleles in                                                                        Probability that                              loci (n)                                                                               (n/2)       new inbred   genotype occurs*                              ______________________________________                                         20      10          14           3 × 10.sup.5                            24      12          16           2 × 10.sup.5                            28      14          18           1 × 10.sup.5                            32      16          20           8 × 10.sup.6                            36      18          22           5 × 10.sup.6                            40      20          24           3 × 10.sup.6                            44      22          26           2 × 10.sup.6                            48      24          28           1 × 10.sup.6                            ______________________________________                                          *Probability that a useful combination exists, does not include the            probability of identifying this combination if it does exist.            

The possibility of having a usably high probability of being able to identify this genotype based on replicated field testing would be most likely smaller than this, and is a function of how large a population of genotypes is tested and how testing resources are allocated in the testing program.

Pioneer research station staff propose about 400 to 500 new inbreds each year from over 2,000,000 pollinations. Of those proposed new inbreds, less than 50, and more commonly less than 30, are actually selected for commercial use.

SUMMARY OF THE INVENTION

According to the invention, there is provided a hybrid maize plant, designated as 3231, produced by crossing two Pioneer Hi-Bred International, Inc. proprietary inbred maize lines. This invention thus relates to the hybrid seed 3231, the hybrid plant produced from the seed, and variants, mutants, and trivial modifications of hybrid 3231. This hybrid maize plant is high yielding and demonstrates excellent stalks, roots and staygreen. Hybrid 3231 is early flowering and demonstrates good grain quality and excellent test weight. Hybrid 3231 performs consistently and demonstrates good drought tolerance and above average resistance to Gray Leaf Spot. It is best adapted for the Central Corn Belt, Western and U.S. Drylands regions of the United States.

DEFINITIONS

In the description and examples that follow, a number of terms are used herein. In order to provide a clear and consistent understanding of the specification and claims, including the scope to be given such terms, the following definitions are provided. NOTE: ABS is in absolute terms and % MN is percent of the mean for the experiments in which the inbred or hybrid was grown. These designators will follow the descriptors to denote how the values are to be interpreted. Below are the descriptors used in the data tables included herein.

ANT ROT=ANTHRACNOSE STALK ROT (Colletotrichum graminicola). A 1 to 9 visual rating indicating the resistance to Anthracnose Stalk Rot. A higher score indicates a higher resistance.

BAR PLT=BARREN PLANTS. The percent of plants per plot that were not barren (lack ears).

BRT STK=BRITTLE STALKS. This is a measure of the stalk breakage near the time of pollination, and is an indication of whether a hybrid or inbred would snap or break near the time of flowering under severe winds. Data are presented as percentage of plants that did not snap in paired comparisons and on a 1 to 9 scale (9=highest resistance) in Characteristics Charts.

BU ACR=YIELD (BUSHELS/ACRE). Yield of the grain at harvest in bushels per acre adjusted to 15.5% moisture.

CLN=CORN LETHAL NECROSIS (synergistic interaction of maize chlorotic mottle virus (MCMV) in combination with either maize dwarf mosaic virus (MDMV-A or MDMV-B) or wheat streak mosaic virus (WSMV)). A 1 to 9 visual rating indicating the resistance to Corn Lethal Necrosis. A higher score indicates a higher resistance.

COM RST=COMMON RUST (Puccinia sorghi). A 1 to 9 visual rating indicating the resistance to Common Rust. A higher score indicates a higher resistance.

CRM=COMPARATIVE RELATIVE MATURITY (see PRM).

D/D=DRYDOWN. This represents the relative rate at which a hybrid will reach acceptable harvest moisture compared to other hybrids on a 1-9 rating scale. A high score indicates a hybrid that dries relatively fast while a low score indicates a hybrid that dries slowly.

D/E=DROPPED EARS. Represented in a 1 to 9 scale in the Characteristics Chart, where 9 is the rating representing the least, or no, dropped ears.

DIP ERS=DIPLODIA EAR MOLD SCORES (Diplodia maydis and Diplodia macrospora). A 1 to 9 visual rating indicating the resistance to Diplodia Ear Mold. A higher score indicates a higher resistance.

DRP EAR=DROPPED EARS. A measure of the number of dropped ears per plot and represents the percentage of plants that did not drop ears prior to harvest.

D/T=DROUGHT TOLERANCE. This represents a 1-9 rating for drought tolerance, and is based on data obtained under stress conditions. A high score indicates good drought tolerance and a low score indicates poor drought tolerance.

EAR HT=EAR HEIGHT. The ear height is a measure from the ground to the highest placed developed ear node attachment and is measured in inches. This is represented in a 1 to 9 scale in the Characteristics Chart, where 9 is highest.

EAR MLD=General Ear Mold. Visual rating (1-9 score) where a "1" is very susceptible and a "9" is very resistant. This is based on overall rating for ear mold of mature ears without determining the specific mold organism, and may not be predictive for a specific ear mold.

EAR SZ=EAR SIZE. A 1 to 9 visual rating of ear size. The higher the rating the larger the ear size.

ECB 1LF=EUROPEAN CORN BORER FIRST GENERATION LEAF FEEDING (Ostrinia nubilalis). A 1 to 9 visual rating indicating the resistance to preflowering leaf feeding by first generation European Corn Borer. A higher score indicates a higher resistance.

ECB 2IT=EUROPEAN CORN BORER SECOND GENERATION INCHES OF TUNNELING (Ostrinia nubilalis). Average inches of tunneling per plant in the stalk.

ECB 2SC=EUROPEAN CORN BORER SECOND GENERATION (Ostrinia nubilalis). A 1 to 9 visual rating indicating post flowering degree of stalk breakage and other evidence of feeding by European Corn Borer, Second Generation. A higher score indicates a higher resistance.

ECB DPE=EUROPEAN CORN BORER DROPPED EARS (Ostrinia nubilalis). Dropped ears due to European Corn Borer. Percentage of plants that did not drop ears under second generation corn borer infestation.

E/G=EARLY GROWTH. This represents a 1 to 9 rating for early growth, scored when two leaf collars are visible.

EST CNT=EARLY STAND COUNT. This is a measure of the stand establishment in the spring and represents the number of plants that emerge on per plot basis for the inbred or hybrid.

EYE SPT=Eye Spot (Kabatiella zeae or Aureobasidium zeae). A 1 to 9 visual rating indicating the resistance to Eye Spot. A higher score indicates a higher resistance.

FUS ERS=FUSARIUM EAR ROT SCORE (Fusarium moniliforme or Fusarium subglutinans). A 1 to 9 visual rating indicating the resistance to Fusarium ear rot. A higher score indicates a higher resistance.

G/A=GRAIN APPEARANCE. Appearance of grain in the grain tank (scored down for mold, cracks, red streak, etc.).

GDU=Growing Degree Units. Using the Barger Heat Unit Theory, that assumes that maize growth occurs in the temperature range 50° F.-86° F. and that temperatures outside this range slow down growth; the maximum daily heat unit accumulation is 36 and the minimum daily heat unit accumulation is 0. The seasonal accumulation of GDU is a major factor in determining maturity zones.

GDU PHY=GDU TO PHYSIOLOGICAL MATURITY. The number of growing degree units required for an inbred or hybrid line to have approximately 50 percent of plants at physiological maturity from time of planting. Growing degree units are calculated by the Barger method.

GDU SHD=GDU TO SHED. The number of growing degree units (GDUs) or heat units required for an inbred line or hybrid to have approximately 50 percent of the plants shedding pollen and is measured from the time of planting. Growing degree units are calculated by the Barger Method, where the heat units for a 24-hour period are: ##EQU1##

The highest maximum temperature used is 86° F. and the lowest minimum temperature used is 50° F. For each inbred or hybrid it takes a certain number of GDUs to reach various stages of plant development.

GDU SLK=GDU TO SILK. The number of growing degree units required for an inbred line or hybrid to have approximately 50 percent of the plants with silk emergence from time of planting. Growing degree units are calculated by the Barger Method as given in GDU SHD definition.

GIB ERS=GIBBERELLA EAR ROT (PINK MOLD) (Gibberella zeae). A 1 to 9 visual rating indicating the resistance to Gibberella Ear Rot. A higher score indicates a higher resistance.

GLF SPT=Gray Leaf Spot (Cercospora zeae-maydis). A 1 to 9 visual rating indicating the resistance to Gray Leaf Spot. A higher score indicates a higher resistance.

GOS WLT=Goss' Wilt (Corynebacterium nebraskense). A 1 to 9 visual rating indicating the resistance to Goss' Wilt. A higher score indicates a higher resistance.

GRN APP=GRAIN APPEARANCE. This is a 1 to 9 rating for the general appearance of the shelled grain as it is harvested based on such factors as the color of harvested grain, any mold on the grain, and any cracked grain. High scores indicate good grain quality.

H/POP=YIELD AT HIGH DENSITY. Yield ability at relatively high plant densities on 1-9 relative rating system with a higher number indicating the hybrid responds well to high plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to increased plant density.

HC BLT=HELMINTHOSPORIUM CARBONUM LEAF BLIGHT (Helminthosporium carbonum). A 1 to 9 visual rating indicating the resistance to Helminthosporium infection. A higher score indicates a higher resistance.

HD SMT=HEAD SMUT (Sphacelotheca reiliana). This score indicates the percentage of plants not infected.

INC D/A=GROSS INCOME (DOLLARS PER ACRE). Relative income per acre assuming drying costs of two cents per point above 15.5 percent harvest moisture and current market price per bushel.

INCOME/ACRE. Income advantage of hybrid to be patented over other hybrid on per acre basis.

INC ADV=GROSS INCOME ADVANTAGE. GROSS INCOME advantage of variety #1 over variety #2.

L/POP=YIELD AT LOW DENSITY. Yield ability at relatively low plant densities on a 1-9 relative system with a higher number indicating the hybrid responds well to low plant densities for yield relative to other hybrids. A 1, 5, and 9 would represent very poor, average, and very good yield response, respectively, to low plant density.

MDM CPX=MAIZE DWARF MOSAIC COMPLEX (MDMV=Maize Dwarf Mosaic Virus and MCDV=Maize Chlorotic Dwarf Virus). A 1 to 9 visual rating indicating the resistance to Maize Dwarf Mosaic Complex. A higher score indicates a higher resistance.

MST=HARVEST MOISTURE. The moisture is the actual percentage moisture of the grain at harvest.

MST ADV=MOISTURE ADVANTAGE. The moisture advantage of variety #1 over variety #2 as calculated by: MOISTURE of variety #2--MOISTURE of variety #1=MOISTURE ADVANTAGE of variety #1.

NLF BLT=Northern Leaf Blight (Helminthosporium turcicum or Exserohilum turcicum). A 1 to 9 visual rating indicating the resistance to Northern Leaf Blight. A higher score indicates a higher resistance.

PHY CRM=CRM at physiological maturity.

PLT HT=PLANT HEIGHT. This is a measure of the height of the plant from the ground to the tip of the tassel in inches. This is represented as a 1 to 9 scale, 9 highest, in the Characteristics Chart.

POL SC=POLLEN SCORE. A 1 to 9 visual rating indicating the amount of pollen shed. The higher the score the more pollen shed.

POL WT=POLLEN WEIGHT. This is calculated by dry weight of tassels collected as shedding commences minus dry weight from similar tassels harvested after shedding is complete.

It should be understood that the inbred can, through routine manipulation of cytoplasmic or other factors, be produced in a male-sterile form. Such embodiments are also contemplated within the scope of the present claims.

POP K/A=PLANT POPULATIONS. Measured as 1000s per acre.

POP ADV=PLANT POPULATION ADVANTAGE. The plant population advantage of variety #1 over variety #2 as calculated by PLANT POPULATION of variety #2--PLANT POPULATION of variety #1=PLANT POPULATION ADVANTAGE of variety #1.

PRM=PREDICTED Relative Maturity. This trait, predicted relative maturity, is based on the harvest moisture of the grain. The relative maturity rating is based on a known set of checks and utilizes standard linear regression analyses and is referred to as the Comparative Relative Maturity Rating System that is similar to the Minnesota Relative Maturity Rating System.

PRM SHD=A relative measure of the growing degree units (GDU) required to reach 50% pollen shed. Relative values are predicted values from the linear regression of observed GDU's on relative maturity of commercial checks.

PRO=PROTEIN RATING. Rating on a 1 to 9 scale comparing relative amount of protein in the grain compared to hybrids of similar maturity. A "1" score difference represents a 0.4 point change in grain protein percent (e.g., 8.0% to 8.4%).

P/Y=PROTEIN/YIELD RATING. Indicates, on a 1 to 9 scale, the economic value of a hybrid for swine and poultry feeders. This takes into account the income due to yield, moisture and protein content.

ROOTS (%)=Percent of stalks NOT root lodged at harvest.

R/L=ROOT LODGING. A 1 to 9 rating indicating the level of root lodging resistance. The higher score represents higher levels of resistance.

RT LDG=ROOT LODGING. Root lodging is the percentage of plants that do not root lodge; plants that lean from the vertical axis as an approximately 300 angle or greater would be counted as root lodged.

RTL ADV=ROOT LODGING ADVANTAGE. The root lodging advantage of variety #1 over variety #2.

S/L=STALK LODGING. A 1 to 9 rating indicating the level of stalk lodging resistance. The higher scores represent higher levels of resistance.

SCT GRN=SCATTER GRAIN. A 1 to 9 visual rating indicating the amount of scatter grain (lack of pollination or kernel abortion) on the ear. The higher the score the less scatter grain.

SDG VGR=SEEDLING VIGOR. This is the visual rating (1 to 9) of the amount of vegetative growth after emergence at the seedling stage (approximately five leaves). A higher score indicates better vigor.

SEL IND=SELECTION INDEX. The selection index gives a single measure of the hybrid's worth based on information for up to five traits. A maize breeder may utilize his or her own set of traits for the selection index. One of the traits that is almost always included is yield. The selection index data presented in the tables represent the mean value averaged across testing stations.

SLF BLT=SOUTHERN LEAF BLIGHT (Helminthosporium maydis or Bipolaris maydis).

A 1 to 9 visual rating indicating the resistance to Southern Leaf Blight. A higher score indicates a higher resistance.

SLK CRM=CRM at Silking.

SOU RST=SOUTHERN RUST (Puccinia polysora). A 1 to 9 visual rating indicating the resistance to Southern Rust. A higher score indicates a higher resistance.

STA GRN=STAY GREEN. Stay green is the measure of plant health near the time of black layer formation (physiological maturity). A high score indicates better late-season plant health.

STAND (%)=Percent of stalks standing at harvest.

STD ADV=STALK STANDING ADVANTAGE. The advantage of variety #1 over variety #2 for the trait STK CNT.

STK CNT=NUMBER OF PLANTS. This is the final stand or number of plants per plot.

STK LDG=STALK LODGING. This is the percentage of plants that did not stalk lodge (stalk breakage) as measured by either natural lodging or pushing the stalks and determining the percentage of plants that break below the ear.

STW WLT=Stewart's Wilt (Erwinia stewarti). A 1 to 9 visual rating indicating the resistance to Stewart's Wilt. A higher score indicates a higher resistance.

TAS BLS=TASSEL BLAST. A 1 to 9 visual rating was used to measure the degree of blasting (necrosis due to heat stress) of the tassel at the time of flowering. A 1 would indicate a very high level of blasting at time of flowering, while a 9 would have no tassel blasting.

TAS SZ=TASSEL SIZE. A 1 to 9 visual rating was used to indicate the relative size of the tassel. The higher the rating the larger the tassel.

TAS WT=TASSEL WEIGHT. This is the average weight of a tassel (grams) just prior to pollen shed.

TEX EAR=EAR TEXTURE. A 1 to 9 visual rating was used to indicate the relative hardness (smoothness of crown) of mature grain. A 1 would be very soft (extreme dent) while a 9 would be very hard (flinty or very smooth crown).

TIL LER=TILLERS. A count of the number of tillers per plot that could possibly shed pollen was taken. Data is given as a percentage of tillers: number of tillers per plot divided by number of plants per plot.

TST WT (CHARACTERISTICS CHART)=Test weight on a 1 to 9 rating scale with a 9 being the highest rating.

TST WT=TEST WEIGHT (UNADJUSTED). The measure of the weight of the grain in pounds for a given volume (bushel).

TST WTA=TEST WEIGHT ADJUSTED. The measure of the weight of the grain in pounds for a given volume (bushel) adjusted for 15.5 percent moisture.

TSW ADV=TEST WEIGHT ADVANTAGE. The test weight advantage of variety #1 over variety #2.

WIN M %=PERCENT MOISTURE WINS.

WIN Y %=PERCENT YIELD WINS.

YLD=YIELD. It is the same as BU ACR ABS.

YLD ADV=YIELD ADVANTAGE. The yield advantage of variety #1 over variety #2 as calculated by: YIELD of variety #1--YIELD variety #2 =yield advantage of variety #1.

YLD SC=YIELD SCORE. A 1 to 9 visual rating was used to give a relative rating for yield based on plot ear piles. The higher the rating the greater visual yield appearance.

DETAILED DESCRIPTION OF THE INVENTION

Pioneer Brand Hybrid 3231 is a single cross, yellow endosperm, dent maize hybrid which is high yielding and demonstrates good drought tolerance. Hybrid 3231 demonstrates excellent stalks, roots and staygreen. Hybrid 3231 demonstrates good grain quality and excellent test weight. This hybrid performs consistently and demonstrates good resistance to Gray Leaf Spot. Hybrid 3231 is early flowering for its maturity. Hybrid 3231 is approximately 115 relative maturity based on the Comparative Relative Maturity Rating System for harvest moisture of grain.

This hybrid has the following characteristics based on the data collected primarily at Johnston, Iowa.

                                      TABLE 1                                      __________________________________________________________________________     VARIETY DESCRIPTION INFORMATION                                                VARIETY = 3231                                                                 __________________________________________________________________________      1.                                                                               TYPE: (describe intermediate types in Comments section):                    2   1 = Sweet 2 = Dent 3 = Flint 4 = Flour 5 = Pop 6 = Ornamental               2.                                                                               MATURITY:                                                                          HEAT                                                                    DAYS   UNITS                                                                   61     1,305                                                                              From emergence to 50% of plants in silk                             61     1,317                                                                              From emergence to 50% of plants in pollen                            6       142                                                                              From 10% to 90% pollen shed                                         73     1,512                                                                              From 50% silk to harvest at 25% moisture                             3.                                                                               PLANT:                          Standard                                                                             Sample                                                                   Deviation                                                                            Size                                  276.0 cm   Plant Height (to tassel tip)                                                                           11.31 2                                     121.0 cm   Ear Height (to base of top ear node)                                                                   9.90  2                                     16.7  cm   Length of Top Ear Internode                                                                            0.71  10                                    1          Average Number of Tillers                                                                              0.00  2                                     1.5        Average Number of Ears per Stalk                                                                       0.71  2                                     1.0        Anthocyanin of Brace Roots:                                                    1 = Absent  2 = Faint  3 = Moderate                                            4 = Dark                                                             4.                                                                               LEAF:                                                                       10.9  cm   Width of Ear Node Leaf  1.84  10                                    89.3  cm   Length of Ear Node Leaf 4.95  10                                    6.2   cm   Number of leaves above top ear                                                                         0.85  10                                    22.5       Degrees Leaf Angle (measure from 2nd leaf                                                              6.36  2                                                above ear at anthesis to stalk above leaf)                          3          Leaf Color  Dark Green  (Munsell code)                                                                             5GY36                           1.0        Leaf Sheath Pubescence (Rate on scale                                          from 1 = none to 9 = like peach fuzz)                               7.5        Marginal Waves (Rate on scale from 1 = none to                                 9 = many)                                                           5.0        Longitudinal Creases (Rate on scale from 1 = none                              to 9 = many)                                                         5.                                                                               TASSEL:                                                                     8.5        Number of Primary Lateral Branches                                                                     0.14  10                                    82.5       Branch Angle from Central Spike                                                                        10.61 2                                     6.5        Pollen Shed (rate on scale from                                                0 = male sterile to 9 = heavy shed)                                 17         Anther  Purple  (Munsell code)      10RP410                         1          Glume Color  Light Green  (Munsell code)                                                                           5GY68                           1.0        Bar Glumes (Glume Bands): 1 = Absent  2 = Present                    6a.                                                                              EAR (Unhusked Data):                                                        14         Silk Color (3 days after emergence) 10RP34 Munsell code)            1          Fresh Husk Color (25 days after 50% silking)  Light Green                      (Munsell code)                      5GY68                           21         Dry Husk Color (65 days after 50% silking)  Buff  (Munsell                     code)                               2.5Y8.54                        1          Position of Ear at Dry Husk Stage: 1 = Upright  2 = Horizontal                  3 = Pendant                        Upright                         5.5        Husk Tightness (Rate of Scale from 1 = very loose to 9 = very                  tight)                                                              2          Husk Extension (at harvest): 1 = Short (ears                                                                       Medium )                                   2 = Medium (<8 cm)  3 = Long (8-10 cm beyond ear tip)                          4 = Very Long (>10 cm)                                               6b.                                                                              EAR (Husked Ear Data):          Standard                                                                             Sample                                                                   Deviation                                                                            Size                                  20.1  cm   Ear Length              3.2526                                                                               10                                    47.6  mm   Ear Diameter at mid-point                                                                              1.4142                                                                               10                                    212.  gm   Ear Weight              72.266                                                                               10                                    16.4       Number of Kernel Rows.  2.2867                                                                               10                                    2          Kernel Rows: 1 = Indistinct  2 = Distinct                                                                          Distinct                        1          Row Alignment: 1 = Straight  2 = Slightly Curved                                                                   Straight                                   3 = Spiral                                                          9.1   cm   Shank Length            3.5355                                                                               10                                    2          Ear Taper: 1 = Slight  2 = Average  3 = Extreme                                                                    Average                          7.                                                                               KERNEL (Dried):                                                             12    mm   Kernel Length           0.5656                                                                               10                                    8.3   mm   Kernel Width            0.1414                                                                               10                                    4.3   mm   Kernel Thickness        0.1414                                                                               10                                    11.8       % Round Kernels (Shape Grade)                                                                          1.3057                                                                               2                                     1          Aleurone Color Pattern: 1 = Homozygous  2 =                                                                        Homozygous                                 Segregating                                                         7          Aluerone Color  Yellow  (Munsell code)                                                                             2.5Y816                         7          Hard Endosperm Color  Yellow  (Munsell code)                                                                       2.5Y816                         3          Endosperm Type:  Normal Starch                                                 1 = Sweet (Su1)  2 = Extra Sweet (sh2)                                         3 = Normal Starch                                                              4 = High Amylose Starch  5 = Waxy Starch                                       6 = High Protein                                                               7 = High Lysine  8 = Super Sweet (se)  9 = High Oil                            10 = Other.sub.--                                                   31    gm   Weight per 100 Kernels (unsized sample)                                                                2.8284                                                                               2                                      8.                                                                               COB:                                                                        25.9  mm   Cob Diameter at mid-point                                                                              0.9899                                                                               10                                    14         Cob Color   Red   (Munsell code)    10R412                          2          Cob Strength  1 = Weak  2 = Strong                                   9.                                                                               DISEASE RESISTANCE                                                             (Rate from 1 (most susceptible) to 9 (most resistant);                         leave blank if not tested; leave Race or Strain Options blank if               polygenic):                                                                 A.   Leaf Blights, Wilts, and Local Infection Diseases                                  Anthracnose Leaf Blight ( Colletotrichum graminicola)                          Common Rust (Puccinia sorghi)                                                  Common Smut (Ustilago maydis)                                         4        Eyespot (Kabatiella zeae)                                             8        Goss's Wilt (Clavibacter michiganense spp. nebraskense)               5        Gray Leaf Spot (Cercospora zeae maydis)                                        Helminthosporium Leaf Spot (Bipolaris zeicola)                        3        Northern Leaf Blight (Exserohilum turcicum)                           5        Southern Leaf Blight (Bipolaris maydis)                               2.5      Southern Rust (Puccinia polysora)                                     3        Stewart's Wilt (Erwinia stewartii)                                             Other (Specify)--                                                     B.   Systemic Diseases                                                         7        Corn Lethal Necrosis (MCMV and MDMV)                                           Head Smut (Sphacelotheca reiliena)                                             Maize Chlorotic Dwarf Virus (MDV)                                              Maize Chlorotic Mottle Virus (MCMV)                                   3        Maize Dwarf Mosaic Virus (MDMV)                                                Sorghum Downy Mildew of Corn (Peronosclerospora sorghi)                        Other (Specify)--                                                     C.   Stalk Rots                                                                3        Anthracnose Stalk Rot (Colletotrichum graminicola)                             Diplodia Stalk Rot (Stenocarpella maydis)                                      Fusarium Stalk Rot (Fusarium moniliforme)                                      Gibberella Stalk Rot (Gibberella zeae)                                         Other (Specify)--                                                     D.   Ear and Kernel Rots                                                                Aspergillus Ear and Kernel Rot (Aspergillus flavus)                            Diplodia Ear Rot (Stenocarpella maydis)                               4        Fusarium Ear and Kernel Rot (Fusarium moniliforme)                             Gibberella Ear Rot (Gibberella zeae)                                           Other (Specify)--                                                     10.                                                                               INSECT RESISTANCE                                                              (Rate from 1 (most susceptible) to 9 (most resistant);                         (leave blank if not tested):                                                         Banks grass Mite (Oligonychus pretensis)                                       Corn Worm (Helicoverpa zea)                                                     Leaf Feeding                                                                   Silk Feeding                                                                   mg larval wt.                                                                 Ear Damage                                                                     Corn Leaf Aphid (Rhopalosiphum maidis)                                         Corn Sap Beetle (Carpophilus dimidiatus)                                       European Corn Borer (Ostrinia nubilalis)                              3.7      1st Generation (Typically Whorl Leaf Feeding)                         5.8      2nd Generation Typically Leaf Sheath-Collar Feeding)                           Stalk Tunneling                                                       2.6   cm tunneled/plant                                                                 Fall Armyworm (Spodoptera fruqiperda)                                           Leaf Feeding                                                                   Silk Feeding                                                                   mg larval wt.                                                                 Maize Weevil (Sitophilus zeamaize)                                             Northern Rootworm (Diabrotica barberi)                                         Southern Rootworm (Diabrotica undecimpunctate)                                 Southwestern Corn Borer (Diatreaea grandiosella)                                Leaf Feeding                                                                   Stalk Tunneling                                                                cm tunneled/plant                                                             Two-spotted Spider Mite (Tetranychus urticae)                                  Western Rootworm (Diabrotica virgifrea virgifera)                              Other (Specify)--                                                        AGRONOMIC TRAITS:                                                           6        Staygreen (at 65 days after anthesis) (Rate on a scale from 1 =                worst to                                                                       excellent)                                                            0.6      % Dropped Ears (at 65 days after anthesis)                                     % Pre-anthesis Brittle Snapping                                                % Pre-anthesis Root Lodging                                           2.9      Post-anthesis Root Lodging (at 65 days after anthesis)                11.030   Kg/ha Yield (at 12-13% grain moisture)                                __________________________________________________________________________

Research Comparisons for Pioneer Hybrid 3231

Comparisons of characteristics for Pioneer Brand Hybrid 3231 were made against Pioneer Brand Hybrids 3162, 3225, 3245, 3279 and 3346.

Table 2A compares Pioneer Hybrid 3231 and Pioneer Hybrid 3162. The results show that Hybrid 3231 is higher yielding and demonstrates a significantly higher test weight than Hybrid 3162. Hybrid 3231 demonstrates an earlier GDU to silk, better resistance to root lodging and better resistance to stalk lodging than Hybrid 3162. Hybrid 3231 demonstrates significantly better staygreen and significantly better resistance to Gray Leaf Spot than Hybrid 3162. Hybrid 3231 also demonstrates lower moisture and better resistance to Southern Leaf Blight than Hybrid 3162. Hybrid 3231 matures earlier than Hybrid 3162 and both hybrids demonstrate above average grain appearance.

Table 2B compares Pioneer Hybrid 3231 and Pioneer Hybrid 3225. The results show that while both hybrids are above average yielding, Hybrid 3231 demonstrates a significantly higher test weight than Hybrid 3225. Hybrid 3231 demonstrates significantly better resistance to root lodging, stalk lodging and Gray Leaf Spot than Hybrid 3225. Hybrid 3231 demonstrates significantly superior staygreen and demonstrates better seedling vigor than Hybrid 3225. Hybrid 3231 is earlier maturing, demonstrates better resistance to Southern Leaf Blight and demonstrates better resistance to Anthracnose Stalk Rot than Hybrid 3225.

Table 2C compares Pioneer Hybrid 3231 and Pioneer Hybrid 3245. The results show that Hybrid 3231 is higher yielding and demonstrates an earlier GDU to silk than Hybrid 3245. Hybrid 3231 demonstrates significantly better resistance to root lodging, stalk lodging and Gray Leaf Spot than Hybrid 3245. Hybrid 3231 also demonstrates significantly superior staygreen than Hybrid 3245.

Table 2D compares Pioneer Hybrid 3231 and Pioneer Hybrid 3279. The results show that Hybrid 3231 is higher yielding and demonstrates a significantly higher test weight than Hybrid 3279. Hybrid 3231 demonstrates better resistance to root lodging, stalk lodging and Gray Leaf Spot than Hybrid 3279. Both hybrids demonstrate above average resistance to brittle stalk. Hybrid 3231 demonstrates significantly superior staygreen and better seedling vigor than Hybrid 3279.

Table 2E compares Pioneer Hybrid 3231 and Pioneer Hybrid 3346. The results show that Hybrid 3231 is significantly higher yielding and demonstrates a significantly higher test weight than Hybrid 3346. Hybrid 3231 demonstrates better resistance to root lodging and Gray Leaf Spot than Hybrid 3346. Both hybrids demonstrate above average resistance to stalk lodging and above average resistance to brittle stalk. Hybrid 3231 demonstrates significantly superior staygreen and significantly better seedling vigor than Hybrid 3346.

                                      TABLE 2A                                     __________________________________________________________________________     VARIETY #1 = 3231                                                              VARIETY #2 = 3162                                                                             PRM BU  BU      TST SDG EST GDU                                            PRM SHD ACR ACR MST WT  VGR CNT SHD                                            ABS ABS ABS % MN                                                                               % MN                                                                               ABS % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   115 112 165.7                                                                              103 104 58.3                                                                               108 99  100                                        2   117 111 163.0                                                                              101 110 56.9                                                                               103 102 99                                         LOCS                                                                               43  40  193 193 201 118 70  104 55                                         REPS                                                                               43  40  246 246 256 134 85  117 65                                         DIFF                                                                               2   1   2.7 2   5   1.4 4   3   1                                          PR > T                                                                             .000#                                                                              .000#                                                                              .063*                                                                              .039+                                                                              .000#                                                                              .000#                                                                              .205                                                                               .004#                                                                              .000#                               __________________________________________________________________________                GDU STK PLT EAR RT  STA STK BRT GRN                                            SLK CNT HT  HT  LDG GRN LDG STK APP                                            % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   99  99  97  96  107 128 103 103 102                                        2   100 101 96  93  104 113 100 103 102                                        LOCS                                                                               30  227 85  80  56  53  124 28  21                                         REPS                                                                               33  294 105 99  75  71  156 35  21                                         DIFF                                                                               1   2   1   3   3   15  3   0   0                                          PR > T                                                                             .077*                                                                              .017+                                                                              .173                                                                               .000#                                                                              .131                                                                               .007#                                                                              .000#                                                                              .999                                                                               .999                                __________________________________________________________________________                DRP GLF NLF SLF GOS STW ANT HD                                                 EAR SPT BLT BLT WLT WLT ROT SMT CLN                                            % MN                                                                               ABS ABS ABS ABS ABS ABS ABS ABS                                 __________________________________________________________________________     TOTAL SUM                                                                             1   100 4.8 3.0 4.7 8.0 3.0 3.4 100.0                                                                              7.0                                        2   100 3.0 3.8 3.0 7.5 4.0 3.4 100.0                                                                              3.5                                        LOCS                                                                               49  9   6   3   1   1   4   1   1                                          REPS                                                                               53  13  11  6   2   2   8   2   2                                          DIFF                                                                               1   1.8 0.8 1.7 0.5 1.0 0.0 0.0 3.5                                        PR > T                                                                             .006#                                                                              .000#                                                                              .199                                                                               .063*       .999                                        __________________________________________________________________________                MDM FUS EYE COM SOU ECB ECB ECB                                                CPX ERS SPT RST RST DPE 1LF 2SC                                                ABS ABS ABS ABS ABS ABS ABS ABS                                     __________________________________________________________________________     TOTAL SUM                                                                             1   2.8 4.3 4.0 5.4 4.3 96.7                                                                               3.3 5.3                                            2   3.0 5.3 5.0 4.8 4.3 100.0                                                                              4.0 5.3                                            LOCS                                                                               1   2   1   6   4   3   2   16                                             REPS                                                                               4   4   1   7   6   3   4   20                                             DIFF                                                                               0.3 1.0 1.0 0.6 0.0 3.3 0.8 0.1                                            PR > T  .705    .180                                                                               .999                                                                               .206                                                                               .656                                                                               .865                                    __________________________________________________________________________      * = 10% SIG                                                                    + = 5% SIG                                                                     # = 1% SIG                                                               

                                      TABLE 2B                                     __________________________________________________________________________     VARIETY #1 = 3231                                                              VARIETY #2 = 3225                                                                             PRM BU  BU      TST SDG EST GDU                                            PRM SHD ACR ACR MST WT  VGR CNT SHD                                            ABS ABS ABS % MN                                                                               % MN                                                                               ABS % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   115 112 162.8                                                                              103 105 57.9                                                                               106 100 101                                        2   116 111 162.9                                                                              103 106 56.5                                                                               99  100 99                                         LOCS                                                                               56  47  249 249 258 141 70  118 64                                         REPS                                                                               56  47  298 298 309 160 84  133 75                                         DIFF                                                                               1   1   0.0 0   2   1.5 7   1   1                                          PR > T                                                                             .004#                                                                              .000#                                                                              .999                                                                               .999                                                                               .001#                                                                              .000#                                                                              .048+                                                                              .582                                                                               .000#                               __________________________________________________________________________                GDU STK PLT EAR RT  STA STK BRT GRN                                            SLK CNT HT  HT  LDG GRN LDG STK APP                                            % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   100 100 97  96  106 128 103 103 99                                         2   100 99  96  95  99  101 100 108 102                                        LOCS                                                                               35  297 102 87  60  51  151 26  16                                         REPS                                                                               38  378 122 106 78  69  184 34  16                                         DIFF                                                                               1   1   0   1   7   27  3   5   3                                          PR > T                                                                             .045+                                                                              .155                                                                               .999                                                                               .272                                                                               .003#                                                                              .000#                                                                              .000#                                                                              .013+                                                                              .636                                __________________________________________________________________________                DRP GLF NLF SLF GOS STW ANT HD                                                 EAR SPT BLT BLT WLT WLT ROT SMT CLN                                            % MN                                                                               ABS ABS ABS ABS ABS ABS ABS ABS                                 __________________________________________________________________________     TOTAL SUM                                                                             1   100 4.9 3.1 5.1 8.0 3.0 3.7 96.2                                                                               6.0                                        2   100 2.9 3.6 3.3 8.0 4.5 2.9 94.6                                                                               6.8                                        LOCS                                                                               71  14  7   4   1   1   8   3   2                                          REPS                                                                               76  23  12  8   2   2   16  6   4                                          DIFF                                                                               0   2.0 0.5 1.9 0.0 1.5 0.8 1.6 0.8                                        PR > T                                                                             .999                                                                               .000#                                                                              .267                                                                               .015+       .005#                                                                              .796                                                                               .656                                __________________________________________________________________________                MDM FUS GIB EYE COM SOU ECB ECB ECB                                            CPX ERS ERS SPT RST RST DPE 1LF 2SC                                            ABS ABS ABS ABS ABS ABS ABS ABS ABS                                 __________________________________________________________________________     TOTAL SUM                                                                             1   2.9 5.4 6.9 4.0 5.5 4.3 97.5                                                                               4.1 5.3                                        2   2.8 5.9 7.1 5.0 5.5 3.3 99.5                                                                               4.0 4.3                                        LOCS                                                                               2   4   2   1   3   4   4   2   15                                         REPS                                                                               7   7   5   1   4   6   6   5   18                                         DIFF                                                                               0.0 0.5 0.2 1.0 0.0 1.0 1.9 0.1 1.1                                        PR > T                                                                             .999                                                                               .182                                                                               .910    .999                                                                               .252                                                                               .371                                                                               .874                                                                               .104                                __________________________________________________________________________                ECB                                                                            2IT                                                                            ABS                                                                 __________________________________________________________________________     TOTAL SUM                                                                             1   2.6                                                                        2   1.3                                                                        LOCS                                                                               1                                                                          REPS                                                                               3                                                                          DIFF                                                                               1.3                                                                        PR > T                                                                  __________________________________________________________________________      * = 10% SIG                                                                    + = 5% SIG                                                                     # = 1% SIG                                                               

                                      TABLE 2C                                     __________________________________________________________________________     VARIETY #1 = 3231                                                              VARIETY #2 = 3245                                                                             PRM BU  BU      TST SDG EST GDU                                            PRM SHD ACR ACR MST WT  VGR CNT SHD                                            ABS ABS ABS % MN                                                                               % MN                                                                               ABS % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   115 112 167.9                                                                              104 105 58.1                                                                               105 99  100                                        2   114 114 166.0                                                                              102 101 58.4                                                                               103 102 102                                        LOCS                                                                               44  50  216 216 225 118 108 113 63                                         REPS                                                                               44  50  275 275 286 139 131 130 75                                         DIFF                                                                               1   2   2.0 2   4   0.2 3   3   2                                          PR > T                                                                             .000#                                                                              .000#                                                                              .205                                                                               .024+                                                                              .000#                                                                              .080*                                                                              .312                                                                               .001#                                                                              .000#                               __________________________________________________________________________                GDU STK PLT EAR RT  STA STK BRT GRN                                            SLK CNT HT  HT  LDG GRN LDG STK APP                                            % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   99  100 95  95  110 126 103 102 94                                         2   103 101 100 96  102 107 99  106 107                                        LOCS                                                                               45  260 103 102 90  87  155 37  45                                         REPS                                                                               49  343 120 118 126 104 203 49  45                                         DIFF                                                                               4   1   4   1   7   20  3   4   13                                         PR > T                                                                             .000#                                                                              .156                                                                               .000#                                                                              .288                                                                               .016+                                                                              .000#                                                                              .001#                                                                              .005#                                                                              .002#                               __________________________________________________________________________                DRP GLF NLF SLF STW ANT HD      MDM                                            EAR SPT BLT BLT WLT ROT SMT CLN CPX                                            % MN                                                                               ABS ABS ABS ABS ABS ABS ABS ABS                                 __________________________________________________________________________     TOTAL SUM                                                                             1   100 5.2 3.3 6.5 5.0 4.0 94.3                                                                               5.0 3.0                                        2   100 4.4 2.6 5.0 4.5 3.3 93.0                                                                               4.5 3.0                                        LOCS                                                                               47  11  5   1   2   4   2   1   3                                          REPS                                                                               52  16  10  2   2   8   4   2   7                                          DIFF                                                                               0   0.8 0.7 1.5 0.5 0.8 1.4 0.5 0.0                                        PR > T                                                                             .999                                                                               .009#                                                                              .077*   .795                                                                               .058*                                                                              .445    .999                                __________________________________________________________________________                FUS GIB EYE SOU ECB ECB ECB ECB                                                ERS ERS SPT RST DPE 1LF 2SC 2IT                                                ABS ABS ABS ABS ABS ABS ABS ABS                                     __________________________________________________________________________     TOTAL SUM                                                                             1   6.5 6.9 4.0 6.0 96.7                                                                               4.1 5.7 2.6                                            2   5.3 6.0 6.0 5.0 98.0                                                                               2.8 5.4 1.8                                            LOCS                                                                               2   2   1   1   3   2   23  1                                              REPS                                                                               4   5   1   1   5   5   33  3                                              DIFF                                                                               1.3 0.9 2.0 1.0 1.3 1.3 0.3 0.8                                            PR > T                                                                             .500                                                                               .361        .433                                                                               .156                                                                               .458                                        __________________________________________________________________________      * = 10% SIG                                                                    + = 5% SIG                                                                     # = 1% SIG                                                               

                                      TABLE 2D                                     __________________________________________________________________________     VARIETY #1 = 3231                                                              VARIETY #2 = 3279                                                                             PRM BU  BU      TST SDG EST GDU                                            PRM SHD ACR ACR MST WT  VGR CNT SHD                                            ABS ABS ABS % MN                                                                               % MN                                                                               ABS % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   115 112 169.5                                                                              104 107 58.2                                                                               108 100 101                                        2   113 112 165.1                                                                              101 102 57.6                                                                               105 101 100                                        LOCS                                                                               34  42  162 162 169 107 77  97  50                                         REPS                                                                               34  42  181 181 190 115 89  108 58                                         DIFF                                                                               2   0   4.4 3   5   0.6 3   1   0                                          PR > T                                                                             .000#                                                                              .999                                                                               .015+                                                                              .012+                                                                              .000#                                                                              .000#                                                                              .372                                                                               .160                                                                               .999                                __________________________________________________________________________                GDU STK PLT EAR RT  STA STK BRT GRN                                            SLK CNT HT  HT  LDG GRN LDG STK APP                                            % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   100 101 96  96  112 125 103 101 96                                         2   100 101 99  98  108 98  101 101 108                                        LOCS                                                                               38  193 77  76  66  59  118 24  31                                         REPS                                                                               39  231 84  82  76  64  132 32  31                                         DIFF                                                                               1   0   3   2   4   27  1   0   12                                         PR > T                                                                             .163                                                                               .999                                                                               .000#                                                                              .061*                                                                              .107                                                                               .000#                                                                              .132                                                                               .999                                                                               .008#                               __________________________________________________________________________                DRP GLF NLF SLF STW ANT HD      MDM                                            EAR SPT BLT BLT WLT ROT SMT CLN CPX                                            % MN                                                                               ABS ABS ABS ABS ABS ABS ABS ABS                                 __________________________________________________________________________     TOTAL SUM                                                                             1   99  5.2 3.2 6.0 5.0 4.0 94.3                                                                               5.0 3.0                                        2   100 4.5 4.5 6.0 6.0 3.6 98.8                                                                               6.0 2.4                                        LOCS                                                                               36  12  3   1   2   4   2   1   3                                          REPS                                                                               41  17  5   1   2   8   4   2   7                                          DIFF                                                                               1   0.7 1.3 0.0 1.0 0.4 4.5 1.0 0.6                                        PR > T                                                                             .038+                                                                              .090*                                                                              .270    .000#                                                                              .391                                                                               .304    .311                                __________________________________________________________________________                FUS GIB EYE SOU ECB ECB ECB ECB                                                ERS ERS SPT RST DPE 1LF 2SC 2IT                                                ABS ABS ABS ABS ABS ABS ABS ABS                                     __________________________________________________________________________     TOTAL SUM                                                                             1   6.5 6.9 4.0 6.0 97.5                                                                               4.1 5.3 2.6                                            2   5.0 7.0 4.0 6.0 95.3                                                                               3.3 4.3 2.1                                            LOCS                                                                               2   2   1   1   4   2   15  1                                              REPS                                                                               3   5   1   1   6   5   18  3                                              DIFF                                                                               1.5 0.1 0.0 0.0 2.2 0.7 1.0 0.5                                            PR > T                                                                             .205                                                                               .910        .698                                                                               .205                                                                               .054*                                       __________________________________________________________________________      * = 10% SIG                                                                    + = 5% SIG                                                                     # = 1% SIG                                                               

                                      TABLE 2E                                     __________________________________________________________________________     VARIETY #1 = 3231                                                              VARIETY #2 = 3346                                                                             PRM BU  BU      TST SDG EST GDU                                            PRM SHD ACR ACR MST WT  VGR CNT SHD                                            ABS ABS ABS % MN                                                                               % MN                                                                               ABS % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   115 112 164.8                                                                              104 106 58.3                                                                               108 100 100                                        2   113 112 157.3                                                                              99  98  57.3                                                                               91  102 100                                        LOCS                                                                               48  45  218 218 228 139 75  104 59                                         REPS                                                                               48  45  253 253 266 160 88  119 66                                         DIFF                                                                               3   0   7.5 5   8   0.9 17  2   0                                          PR > T                                                                             .000#                                                                              .999                                                                               .000#                                                                              .000#                                                                              .000#                                                                              .000#                                                                              .000#                                                                              .160                                                                               .999                                __________________________________________________________________________                GDU STK PLT EAR RT  STA STK BRT GRN                                            SLK CNT HT  HT  LDG GRN LDG STK APP                                            % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                                                               % MN                                __________________________________________________________________________     TOTAL SUM                                                                             1   100 100 96  96  112 127 103 103 96                                         2   99  101 96  99  102 106 104 102 100                                        LOCS                                                                               40  252 85  76  64  59  143 27  28                                         REPS                                                                               43  306 93  83  75  65  172 33  28                                         DIFF                                                                               1   1   0   3   10  20  1   1   4                                          PR > T                                                                             .077*                                                                              .135                                                                               .999                                                                               .029+                                                                              .015+                                                                              .001#                                                                              .213                                                                               .730                                                                               .302                                __________________________________________________________________________                DRP GLF NLF SLF STW ANT HD      MDM                                            EAR SPT BLT BLT WLT ROT SMT CLN CPX                                            % MN                                                                               ABS ABS ABS ABS ABS ABS ABS ABS                                 __________________________________________________________________________     TOTAL SUM                                                                             1   100 5.2 3.2 6.5 5.0 4.0 94.3                                                                               5.0 3.3                                        2   100 4.0 4.3 7.0 5.0 4.8 100.0                                                                              4.0 3.3                                        LOCS                                                                               55  12  3   1   2   4   2   1   2                                          REPS                                                                               59  17  5   2   2   8   4   2   5                                          DIFF                                                                               0   1.2 1.2 0.5 0.0 0.8 5.7 1.0 0.1                                        PR > T                                                                             .999                                                                               .004#                                                                              .336    .999                                                                               .103                                                                               .126    .874                                __________________________________________________________________________                FUS GIB EYE COM ECB ECB ECB ECB                                                ERS ERS SPT RST DPE 1LF 2SC 21T                                                ABS ABS ABS ABS ABS ABS ABS ABS                                     __________________________________________________________________________     TOTAL SUM                                                                             1   6.5 6.9 4.0 6.0 98.0                                                                               4.1 5.0 2.6                                            2   3.3 6.8 3.0 6.0 94.9                                                                               3.7 4.6 1.3                                            LOCS                                                                               2   2   1   1   3   2   11  1                                              REPS                                                                               3   5   1   1   5   5   13  3                                              DIFF                                                                               3.3 0.1 1.0 0.0 3.0 0.4 0.5 1.3                                            PR > T                                                                             .234                                                                               .963        .647                                                                               .126                                                                               .360                                        __________________________________________________________________________      * = 10% SIG                                                                    + = 5% SIG                                                                     # = 1% SIG                                                               

Strip Test Data for Hybrid 3231

Comparison data was collected from strip tests that were grown by farmers. Each hybrid was grown in strips of 4, 6, 8, 12, etc. rows in fields depending on the size of the planter used. The data was collected from strip tests that had the hybrids in the same area and weighed. The moisture percentage was determined and bushels per acre was adjusted to 15.5 percent moisture. The number of comparisons represent the number of locations or replications for the two hybrids that were grown in the same field in close proximity and compared.

Comparison strip testing was done between Pioneer Brand Hybrid 3231 and Pioneer Brand Hybrids 3225, 3245, 3279, 3346 and 3162. The comparisons come from all the hybrid's adapted growing areas in the United States.

These results are presented in Table 3. Hybrid 3231 has a weighted average 2.5 bushels per acre yield advantage and a $6.57 per acre income advantage over the other hybrids. Hybrid 3231 also has a weighted average 2 percentage point stand advantage, a 1 percentage point root advantage and a 1.2 pound per bushel test weight advantage over the other hybrids.

                                      TABLE 3                                      __________________________________________________________________________     1995 PERFORMANCE COMPARISON REPORT FOR CORN                                    1 YEAR SUMMARY OF ALL STANDARD TEST TYPES.                                                            Income/                                                                            Pop Stand                                                                              Roots                                                                              Test                                    Brand      Product                                                                            Yield                                                                              Moist                                                                              Acre                                                                               K/Acre                                                                             (%) (%) Wt                                      __________________________________________________________________________     PIONEER    3231                                                                               148.9                                                                              19.4                                                                               359.66                                                                             24.6                                                                               95  91  57.9                                    PIONEER    3225                                                                               149.4                                                                              20.4                                                                               358.06                                                                             24.6                                                                               92  91  56.5                                    Advantage      -0.5                                                                               1.0 1.60                                                                               0.0 3   0   1.4                                     Number of Comparisons                                                                         249 249 249 87  65  57  245                                     Percent Wins   44  71  48  36  52  5   81                                      Probability of Difference                                                                     44  99  58  16  99  18  99                                      PIONEER    3231                                                                               156.3                                                                              19.2                                                                               378.38                                                                             25.4                                                                               95  100 58.3                                    PIONEER    3245                                                                               153.1                                                                              18.0                                                                               373.64                                                                             25.0                                                                               96  97  59.0                                    Advantage      3.2 -1.2                                                                               4.74                                                                               0.4 -1  3   -0.7                                    Number of Comparisons                                                                         114 114 114 36  32  31  79                                      Percent Wins   62  16  57  52  21  16  12                                      Probability of Difference                                                                     99  99  88  73  76  91  99                                      PIONEER    3231                                                                               142.1                                                                              20.1                                                                               341.19                                                                             24.0                                                                               96  99  58.1                                    PIONEER    3279                                                                               138.9                                                                              19.5                                                                               335.25                                                                             23.8                                                                               93  98  57.0                                    Advantage      3.2 -0.6                                                                               5.94                                                                               0.2 3   1   1.1                                     Number of Comparisons                                                                         161 161 161 66  60  56  140                                     Percent Wins   59  34  58  37  40  5   75                                      Probability of Difference                                                                     99  99  98  50  99  88  99                                      PIONEER    3231                                                                               147.8                                                                              19.4                                                                               356.83                                                                             24.6                                                                               96  99  58.0                                    PIONEER    3346                                                                               142.3                                                                              17.8                                                                               347.21                                                                             24.4                                                                               96  99  56.9                                    Advantage      5.5 -1.6                                                                               9.62                                                                               0.2 0   0   1.1                                     Number of Comparisons                                                                         195 195 195 34  21  17  163                                     Percent Wins   68  7   63  44  38  5   73                                      Probability of Difference                                                                     99  99  99  36  7   37  99                                      PIONEER    3231                                                                               155.8                                                                              19.2                                                                               376.95                                                                             24.7                                                                               95  98  58.1                                    PIONEER    3162                                                                               153.3                                                                              20.8                                                                               366.47                                                                             24.9                                                                               94  97  56.6                                    Advantage      2.5 1.6 10.48                                                                              -0.2                                                                               1   1   1.5                                     Number of Comparisons                                                                         242 242 242 77  59  50  220                                     Percent Wins   49  83  54  37  42  4   79                                      Probability of Difference                                                                     99  99  99  49  45  66  99                                      PIONEER    3231                                                                               150.1                                                                              19.5                                                                               362.57                                                                             24.6                                                                               95  97  58.1                                    WEIGHTED AVG   147.6                                                                              19.5                                                                               356.00                                                                             24.5                                                                               93  96  56.9                                    Advantage      2.5 0.0 6.57                                                                               0.1 2   1   1.2                                     Number of Comparisons                                                                         961 961 961 300 237 211 847                                     Percent Wins   55  48  55  40  41  6   71                                      Probability of Difference                                                                     99  78  99  36  99  81  99                                      __________________________________________________________________________      NOTE: The probability values are useful in analyzing if there is a "real"      difference in the genetic potential of the products involved. High values      are desirable, with 95% considered significant for real differences.     

Comparison of Key Characteristics for Hybrid 3231

Characteristics of Pioneer Hybrid 3231 are compared to Pioneer Hybrids in Table 4. The values given for most of the traits are on a 1-9 basis. In these cases 9 would be outstanding, while 1 would be poor for the given characteristics. These values are based on performance of a given hybrid relative to the Pioneer commercial, precommercial and competitive hybrids that are grown in research strip test trials. These performance based values are determined utilizing several factors such as research data, experience the trained corn researchers had in the field, and the sales experience with the hybrids in strip tests in the field. These values reflect the hybrid's relative performance to other hybrids for the characteristics listed. Table 4 shows Hybrid 3231 is very high yielding in both normal and low plant density environments. Hybrid 3231 also demonstrates good resistance to root lodging and a high test weight. Hybrid 3231 demonstrates very good ratings for a unique combination of characteristics including yield, resistance to stalk lodging, resistance to root lodging, staygreen, drought tolerance, test weight, early growth and protein yield.

                                      TABLE 4                                      __________________________________________________________________________     Hybrid Patent Comparisons-Characteristics                                      Pioneer Hybrid 3231 vs. Pioneer Hybrids 3225, 3245, 3279, 3346,                and 3162                                                                               SILK                                                                              PHY                                                                               GDU                                                                               GDU   H/ L/                                                   VARIETY                                                                             CRM                                                                               CRM                                                                               CRM                                                                               SILK                                                                              PHY                                                                               YLD                                                                               POP                                                                               POP                                                                               D/D                                                                               S/L                                                                               R/L                                         __________________________________________________________________________     3231 115                                                                               112                                                                               113                                                                               1400                                                                              2750                                                                              9  8  9  4  7  8                                           3225 115                                                                               113                                                                               113                                                                               1410                                                                              2750                                                                              9  9  8  5  4  5                                           3245 115                                                                               115                                                                               114                                                                               1440                                                                              2770                                                                              8  7  8  6  5  4                                           3279 113                                                                               113                                                                               112                                                                               1410                                                                              2720                                                                              8  7  9  6  5  7                                           3346 113                                                                               111                                                                               112                                                                               1390                                                                              2720                                                                              8  9  8  6  8  4                                           3162 118                                                                               112                                                                               113                                                                               1400                                                                              2770                                                                              9  9  8  3  5  7                                           __________________________________________________________________________          STA   TST   PLT                                                                               EAR   BRT                                                  VARIETY                                                                             GRN                                                                               D/T                                                                               WT E/G                                                                               HT HT D/E                                                                               STK                                                                               PRO                                                                               P/Y                                            __________________________________________________________________________     3231 8  8  8  7  4  4  4  5  4  8                                              3225 4  7  6  5  3  4  5  8  4  8                                              3245 5  5  8  5  6  4  5  6  6  9                                              3279 5  8  7  7  5  4  5  5  5  8                                              3346 9  9  5  3  4  5  4  5  5  8                                              3162 5  7  7  6  4  4  5  7  5  8                                              __________________________________________________________________________

INDUSTRIAL APPLICABILITY

This invention includes hybrid maize seed of 3231 and the hybrid maize plant produced therefrom. The foregoing was set forth by way of example and is not intended to limit the scope of the invention.

As used herein, the term plant includes plant cells, plant protoplasts, plant cell tissue cultures from which maize plants can be regenerated, plant calli, plant clumps, and plant cells that are intact in plants, or parts of plants, such as embryos, pollen, ovules, flowers, kernels, ears, cobs, leaves, seeds, husks, stalks, roots, root tips, anthers, silk and the like.

Duncan, Williams, Zehr, and Widholm, Planta, (1985) 165:322-332 reflects that 97% of the plants cultured which produced callus were capable of plant regeneration. Subsequent experiments with both inbreds and hybrids produced 91% regenerable callus which produced plants. In a further study in 1988, Songstad, Duncan & Widholm in Plant Cell Reports (1988), 7:262-265 reports several media additions which enhance regenerability of callus of two inbred lines. Other published reports also indicated that "nontraditional" tissues are capable of producing somatic embryogenesis and plant regeneration. K. P. Rao, et al., Maize Genetics Cooperation Newsletter, 60:64--65 (1986), refers to somatic embryogenesis from glume callus cultures and B. V. Conger, et al., Plant Cell Reports, 6:345-347 (1987) indicates somatic embryogenesis from the tissue cultures of maize leaf segments. Thus, it is clear from the literature that the state of the art is such that these methods of obtaining plants are, and were, "conventional" in the sense that they are routinely used and have a very high rate of success.

Tissue culture of maize is described in European Patent Application, publication 160,390, incorporated herein by reference. Maize tissue culture procedures are also described in Green and Rhodes, "Plant Regeneration in Tissue Culture of Maize," Maize for Biological Research (Plant Molecular Biology Association, Charlottesville, Virginia 1982, at 367-372) and in Duncan, et al., "The Production of Callus Capable of Plant Regeneration from Immature Embryos of Numerous Zea Mays Geneotypes," 165 Planta 322-332 (1985). Thus, another aspect of this invention is to provide cells which upon growth and differentiation produce maize plants having the genotype of 3231.

Maize is used as human food, livestock feed, and as raw material in industry. The food uses of maize, in addition to human consumption of maize kernels, include both products of dry- and wet-milling industries.

Maize, including both grain and non-grain portions of the plant, is also used extensively as livestock feed, primarily for beef cattle, dairy cattle, hogs, and poultry.

Industrial uses of maize include production of ethanol, maize starch in the wet-milling industry and maize flour in the dry-milling industry. The industrial applications of maize starch and flour are based on functional properties, such as viscosity, film formation, adhesive properties, and ability to suspend particles. The maize starch and flour have application in the paper and textile industries. Other industrial uses include applications in adhesives, building materials, foundry binders, laundry starches, explosives, oil-well muds, and other mining applications.

Plant parts other than the grain of maize are also used in industry. Stalks and husks are made into paper and wallboard and cobs are used for fuel and to make charcoal.

The seed of the hybrid maize plant and various parts of the hybrid maize plant can be utilized for human food, livestock feed, and as a raw material in industry.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity and understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the invention, as limited only by the scope of the appended claims.

Applicants have made a deposit of at least 2500 seeds of Hybrid Maize Line 3231 with the American Type Culture Collection (ATCC), Rockville, Md. 20852 USA, ATCC Deposit No. 209332. The seeds deposited with the ATCC on Oct. 6, 1997 were taken from the deposit maintained by Pioneer Hi-Bred International, Inc., 700 Capital Square, 400 Locust Street, Des Moines, Iowa 50309-2340 since prior to the filing date of this application. This deposit of the Hybrid Maize Line 3231 will be maintained in the ATCC depository, which is a public depository, for a period of 30 years, or 5 years after the most recent request, or for the enforceable life of the patent, whichever is longer, and will be replaced if it becomes nonviable during that period. Additionally, Applicant has satisfied all the requirements of 37 C.F.R. §§1.801-1.809, including providing an indication of the viability of the sample. Applicant imposes no restrictions on the availability of the deposited material from the ATCC; however, Applicant has no authority to waive any restrictions imposed by law on the transfer of biological material or its transportation in commerce. Applicant does not waive any infringement of its rights granted under this patent. 

I claim:
 1. Hybrid maize seed designated 3231, representative seed of said hybrid 3231 having been deposited under ATCC accession number
 209332. 2. A maize plant, or its parts, produced by the seed of claim
 1. 3. Pollen of the plant of claim
 2. 4. An ovule of the plant of claim
 2. 5. A tissue culture of regenerable cells of a hybrid maize plant 3231, representative seed of said hybrid maize plant 3231 having been deposited under ATCC accession number 209332, wherein the tissue regenerates plants capable of expressing all the morphological and physiological characteristics of said hybrid maize plant
 3231. 6. A tissue culture according to claim 5, the cells or protoplasts being of a tissue selected from the group consisting of leaves, pollen, embryos, roots, root tips, anthers, silks, flowers, kernels, ears, cobs, husks, and stalks.
 7. A maize plant, or its parts, regenerated form the tissue culture of claim 5 and capable of expressing all the morphological and physiological characteristics of hybrid maize plant 3231, representative seed having been deposited under ATCC accession number
 209332. 